1. Field of the Invention
This invention relates to metal tubing of the type commonly used to form furniture, and the like, and, more particularly, to a die for forming discrete notches/cut-outs in the tubing.
2. Background Art
It is known to provide discrete notches in hollow tubing to facilitate interconnection of tubing pieces. This construction technique is commonly employed in fabricating furniture such as desks, stands, and the like
One problem that metal fabricators have contended with is that of forming the notches/cut-outs without appreciably deforming the tubular stock. This problem can be obviated by cutting or grinding the notches/cut-outs from the tubular stock, however such procedures are time consuming, expensive, imprecise, and thus impractical.
Ideally, the notches are made using a press setup through which a notch can be simply formed by a single stroke of a ram on the press. To avoid collapse of the tubing on a press setup, a female core die is generally inserted in the hollow of the tube. A male die is then directed through the tubing and is backed by the female die.
There are several drawbacks with systems utilizing a core die. First, the internal cross section of tubular stock is not uniform. Dimensions may vary from one manufacturer to the next. Further, the stock from one fabricator is commonly non-uniform. Frequently, burrs and welds project into the hollow and thereby impede or prevent the insertion of a female core die. Also, long workpieces do not lend themselves to the use of core dies.
Further, the female die, under extreme pressure, may be damaged in the forming process. In the event that the tube is deformed with the core die in place, it may be difficult or impossible to remove the core die after the notch/cut-out is formed.
A further drawback with the core dies is that they are complicated to use. One must stock core dies for all different tube configurations. Further, the insertion of the die is a meticulous process that is time consuming and results in an overall increase in manufacturing costs.
Another problem with conventional press setups is that they generally utilize a male die that has a substantial surface area which contacts the tube stock at the initiation of the press operation. The result is that the cutting die is severely stressed, thereby making it prone to failure and shortening its useful life. Further, the large surface area on the press forcibly advanced against the tubing may result in spring back or explosion thereof, the danger of which is apparent.
The present invention is specifically directed to overcoming the above-enumerated problems in a novel and simple manner.